[KansasCityGT]

So, if any of you have read my last thread about overheating, I have since changed the head gaskets, again, last week. The car does not overheat anymore. But the temp gauge does climb to the larger 3/4 mark when on the highway. When idling, city driving or heat is on full blast when on the highway, it is just above the large 1/4 mark, where it was in the past before issues started. I am not sure, I can only assume that the coolant system was burped. Just in case, about 15 minutes ago, I parked the car on a nice incline, removed the radiator cap, turned on heat and idled for about 20 minutes "no overheating" to remove any air from the system. I'll monitor today when on the highway. Second thing I notice, when over 40mph there is a drone/vibration when under acceleration. When coasting, it is fine. This was not happening prior to pulling the engine and changing the head gaskets. I don't feel like it is a tire balance. I feel it has something to do with engine when under acceleration. But why would 40mph make a difference, wouldn't the rpm matter more?

-Gianni

 

[adc]

When the vehicle is cold check the radiator level. Also I would suggest replacing the radiator cap with a genuine subaru cap.

 

[BigBopper]

A couple things to consider:
Running hot ...

• Thermostat - Did you change it out? Is it in good working order?
  (^ I agree with the OEM Rad Cap replacement recommendation)
• How did your anti-freeze look when you drained it?
• Rad core in good shape?
• Did you fill with OEM anti-freeze and conditioner?

Vibration ...
I took from your comments that it could be drive line related. :shrug:
What comes to mind for me is:

• Motor mounts ... installed properly, good shape, tight?
• Transmission mounts ... were they loosened, then tightened properly after engine install?
• Clutch, pressure plate & throw-out bearing ... How did they look? Did you replace or clean/lube existing throw-out bearing?
• Axle Nuts ... properly tightened?

Hope you get it sorted out.